ARC Centre of Excellence in Synthetic Biology

Synthetic Biology

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15, Feb 2024

Microbial marvels turn waste gases into green gold

What if we could encourage microbes to eat greenhouse gases being pumped into our atmosphere at alarming levels and create sustainable fuels, chemicals and materials instead?

In essence, that’s what happening with companies such as the Centre’s partner LanzaTech, who are making headlines with innovative new products produced using their breakthrough carbon recycling processes.

And it’s at the heart of innovative research at the University of Queensland (UQ) node which specialises in gas fermentation solutions using one of nature’s tiny allies.

The UQ team, spearheaded by James Heffernan and Karen Rodriguez Martinez focus on Clostridium autoethanogenum, a bacterium with a knack for capturing and converting greenhouse gases into ethanol, a clean and useful product that can be used as either a fuel or a chemical.

‘The aim is to be able to take waste gas streams produced by industry, solid waste streams that can be converted into a gas such as municipal solid waste or agricultural residues, or even concentrated streams of CO2 together with green hydrogen; and convert each into sustainably produced commodities,’ says James.

The team has worked on various approaches to improving gas fermentation for industry. One project aimed to explore how much carbon dioxide these bacteria could capture in conjunction with hydrogen, and turn into useful products such as ethanol.

To understand this better, the scientists used computer models to predict how the bacteria would perform under different conditions. The models hinted at a solution – adjusting the bacteria’s metabolism, especially by introducing a small amount of carbon monoxide (CO). This addition would act as a supercharger, significantly enhancing the bacteria’s productivity in utilising waste carbon.

Eager to explore further, the team introduced a mix of carbon monoxide, carbon dioxide, and hydrogen to the bacteria in bioreactors. The addition of just two percent CO more than doubled the production of biomass, ethanol and acetate, and demonstrated a more efficient use of carbon. More than half of the captured carbon found a new life as ethanol, marking a significant breakthrough in sustainable fuel and chemical production.

This discovery promises more efficient ways to transform waste gases from industrial processes into valuable and sustainable raw materials.

‘We’re excited about the potential of acetogenic bacteria and their ancient yet ingenious metabolic processes,’ says James.  ‘This small step brings us significantly closer to a future where industries are more sustainable, and our impact on the planet is greatly reduced. All thanks to the power of microscopic heroes.’

‘It’s thrilling to be able to work with true innovators in the field, such as LanzaTech. With the Swiss sports brand On they just announced a collection of sports apparel made from carbon emissions. That’s incredibly exciting stuff.’

‘We hope that our work on fuels will lead to more products and more potential in the rapidly expanding field of sustainable biomanufacturing.’